Straight from the press release:
“As with all Apple products, powerful accessibility features have been built right into visionOS. Key accessibility features like VoiceOver, Zoom, Switch Control, Guided Access, and more have been reimagined for spatial computing. Users can interact with Apple Vision Pro entirely with their eyes, hands, or voice, or any combination that works best for them. They can select a preferred input method such as their eyes, finger, or wrist using Pointer Control, pause on an element of visionOS for a few seconds to simulate a tap using Dwell Control, or simply use voice commands for activities across Vision Pro using Voice Control. If input from both eyes is not an option, visionOS also allows eye tracking with one dominant eye.”
So yes, it works with only one dominant eye, or no eyes if you happen to not have any.